Britain has been colonised by many foreign nations throughout its history but one period in particular has generated a fierce debate in the archaeological world. It centres on the occupation of Atlantic Scotland (the northern and western mainland of Scotland along with the Western and Northern Island chains) by the Norse peoples in the 8th-10th centuries and two competing theories have evolved to describe this period.

The first proposes a long and peaceful occupation of more than 100 years while the other suggests that the occupation was short and sharp over a 50-year period. The former argument relies heavily on the discovery of combs made from reindeer, which were absent from Britain but common in Scandinavia. Red deer and roe deer were common in Britain at the time.

Now, an analysis of the collagen present in ancient combs made from antler and bone has helped edge the parties towards a resolution. Scientists from the UK and Israel used mass spectrometry to examine the collagen peptides in combs excavated from five sites in Orkney, including those labelled as native and Norse types, as well as control combs from North Yorkshire. The results, published in Journal of Archaeological Science and confirmed by DNA analysis, show that combs previously thought to be of reindeer antler were, in fact, red deer. The only combs made from antler were typically Norse.

This suggests that the local people in Scotland did not have access to Scandinavian materials like antler. "The balance of evidence no longer supports the existence of a long period of cultural contact between Atlantic Scotland and Scandinavian settlers before the late 9th century," say the research team.

This is the first time that this analytical technique, known as ZooMS (Zooarchaeology by mass spectrometry), has been applied to identify the animal origin of bone and antler. It had a higher success rate than DNA analysis, probably because collagen is more stable over time than DNA, and uses minute amounts of sample. It should be a useful archaeological tool.